Fan for liquid fuel burners



96E. 1 H. E. HENRIKSEN 2,218,543

' FAN FOR LIQUID FUEL BURNERS I Filed Dec. 13, 1937 4 Sheets- Sheet 1 l I'filllllllllllllllllllllll, Mm ,Itl a llI- glllllllllllllllllllllll MMLELIJELIJLILLU II IIIIIIIIlllllllllllllllillllllll ATTORNEY.

Oct; 22, 1940.

H. E. HENRIKSEN FAN FOR LIQUID FUEL BURNERS' Filed Dec. 15, 195'! 4 Sheets- Sheet 2 ATTOR-NEY.

Oct. 22, 1940. H. E. HENRIKSEN 2,218,643

- FAN FOR LIQUID FUEL BURNERS Filed Dec. 13, 1937 4 Sheets-Sheet 3 ATTORNEY.

Oct. 22, 1940. H. E. HENRIKSEN FAN FOR LIQUID FUEL BURNER;

Filed Dec. 15. 1937 4 Sheets-Sheet 4 INVENTOR fiJ/il/eg fienr/ksen BY M W ATTORNEY Patented Oct. 22, 1940 FAN roa LIQUID FUEL BUBNERS San mat-1m, 03111., as-

Harvey E. Henriksen,

signor to Ray Oil Burner 00.,

Calii'., a corporation of Delaware Application Decem ber 13, 1937, Serial No. 179,502

13 Claims.

This invention relates to oil burners of the type in which oil in finely divided or atomized form is fed mixed with air, tothe locus of combustion and more particularly to the fan thereof, its coordination therewith, and the control of the supply of fuel and air. My burner is pref erably of the horizontal type, the oil being spun oil of or out of a rotating .cup mounted in the burner casing. A fan is usually in the burner casing for directing a blast of air into an annular space formed between the cup and 'a nozzle surrounding it, this blast of air aiding in the subdivision of the oil spun ofi by the cup and serving as the primary supply of air for combustion. An additional or secondary supply of air for combustion may flow through an annular space between the nozzle and a burner hinge plate which, as is the custom, may be attached to the furnace wall.

Oil burners of this type have heretofore been not all that could be desired insofaras emclency isconcerned because very little attention was given to .the air flow through the burner, so as not to create turbulence causing loss in emciency. Furthermore, the proper coordination of the flow of air and the flow of fuel oil is another factor that has to be considered in this connection. The amount of air required in actual practice is not. actually, regardless of theory, proportional to the amount of oil being burned, and the changes in the rate of air flow as the rate of oil flow is changed have been made more or less empirically in actual practice, by guess of the operator.

Objects of my invention are to increase the efliciency of preparing and burning the fuel; to overcome the difllculties and disadvantages of prior devices; to provide an oil burner having increased output horsepower per unit of oil consumed and per unit of power consumed in the operation of the burner, and to increase generally the burner efliciency; to provide a smaller size burner which will have a power output equal to that of larger size burners heretofore used; to provide a burner which will have a greater power output than burners of the same size heretofore used; to make the air feed to the burner more eflicient than heretofore; to avoid noisy operation; to simplify the control of air and of oil; to provide a simple,. easily operable means for simultaneously controlling both the supply of oil and the supply of air; to provide an air-feed control dependent on the oilteed control and .which automatically varies the 5 ratio or air to oil in the particular manner round s PATENT oi-"rlcs San Francisco,

specification.

Generally stated, my invention comprises making substantially uniform the cross sectional area of the path of the air through my device, and particularly at the inlet of and after entering the fan, so that there is no squeezing or expansion of the air in its path and all flow is translated' into straight velocity with minimum turbulence or eddy currents; by having such air flow to the fan inlet without hindrance thereto to avoid turbulence or eddy currents; by having the fan blades begin at a vpoint set forward on the hub as compared to straight radial blades so as to provide for increased length of the blades and thereby enable the fan ,to handle a greater volume of air with greater pressure; by having the fan blades curved at the inlet opening of the fan to provide streamline flow at theinlet and thereby avoid turbulence, and then straight from the inlet opening to the outer the fan so as to prevent change of periphery oi direction of the air while being guided between the vanes;

by arranging the angle of discharge of the fan blades so as to decrease the tangential compo nent of -movement of the'air after it leaves the fan blades and thereby reduce turbulence; by

providing a means to receive by the fan blades to the fan that change of the air thrown out which is so co-related direction of movement of the air is decreased; and by having vanes in the nozzle to impart a rotary movement to the air. I also provide a means operable by an adjusting lever or other simple control for changply of air. The optimum rate of feed of such air is predetermined for each I oil, and there is a means rate of feed of such to co-ordinate the rate of air flow to whatever rate of fuel oil flow is my invention on which in operation, so that -flow occurs in any posisimple control means.

embodiment of ing the rate of feed of the Iueloil and simul- I taneously the rate of iced of the primary sup-v the accompanying drawings which form a part oi! this specification and on Fig. 1 is a plan view of my burner;

Fig. 2 is a rear elevation thereof;

Fig. 3 is a cross-section taken on the line 3-3 of Fig. 4 looking in the direction of the arrows, with parts in elevation;

Fig. 4 is a cross-section on the line 44 of Fig. 3, looking in the direction of the arrows;

Fig. 5 is a side elevation from the right of Fig. 2, showing the control handle and appurtenant parts;

Fig. 6 is an elevational view of the fan, taken in a plane indicated by line 6-6 of Fig. 3, and looking in the direction of the arrows, with parts broken away to illustrate more clearly the construction;

Fig. 7 is an elevation viewed along the line 63 of Fig. 3, but looking to the left thereof, with parts broken away;

Fig. 8 is a sectional elevation of Fig. 6 on the line 88 thereof, looking in the direction of he arrows;

Fig. 9 is a sectional elevation of Fig. 7 on the line 99 thereof, looking in the direction of the arrows;

Fig. 10 is an elevation of the outlet nozzle looking in the direction of arrow ID in Fig. 3;

Fig. 11 is a cross section thereof; and

Fig. 12 is a cross section on the line |2|2 of Fig. 3, but on a reduced scale.

The various views of the drawings illustrate the correct contour and proportions of the variour parts and their relationship with respect to each other, as actually employed on my burner.

The greater part of my device is enclosed within a casing 2| which has an opening 22, preferably at the bottom thereof. An electric motor 23 is supported within the casing by contact with lugs 24, 25, 26, and 2i. The motor shaft 28 is hollow, and within it is a stationary pipe 29 screwed into a hollow lug 36 on a casing cap 3| which is suitably fastened-to the casing 2| by screws 32. A fan hub 33 is attached to .the hollow motor shaft 28 by means of one or more screws 34 passing through the fan hub and vbearing against the shaft. The fan comprises a plate 35 attached by screws 36 to an impeller plate 31 having a central opening 38 and impeller vanes or blades 39 extending from the center thereof to the periphery. The impeller blades are not truly radial, but each blade leaves the hub 33 almost tangentially thereto at a point 4| preferably at a lead of about eightysix and one-half degrees (86%") ahead, in the direction of rotation, of the point 42 at the intersection of the hub with a theoretical radius 43 which extends outwardly to the point 44 where the blade ends at the periphery of the plate. Each impeller blade 39 is curved between the point 4| and the point 45 at which it meets the edge of the fan inlet, in such a manner that it is streamlined and thereby avoids turbulence and eddy currents. From the point 45 on out to the point 44 at the periphery of the fan it is straight and makes an angle 39a of about twentytwo degrees (22) with its theoretical radius 43. A substantially greater angle results in slippage and loss of efllciency. Eachblade 39v has the same characteristics. Between each two adjacent blades 39 are blades 46 which have the same characteristics as the blades 39 except that they extend only from the inner periphery to the outer periphery of the annular plate 31, that is, from the periphery of the fan inlet to the periphery of the fan. The total number of blades is preferably l4, spaced thirty-six degrees (36) apart; and preferably all the blades and.

the impeller plate 31 are formed as a unitary casting. The blades 46 could be the same as the blades 39 and have a similar curved part extending to the hub. It is desirable, however, in a device of the dimensions indicated by the accompanying drawings to omit this curved part in order to provide a greater space for the entry of air into the fan. For example, in a device which is suiliciently large or in one which has a sufficiently large hub, the blades 46 may be complete and substantially the same as the blades 39. Any of the blades, for example the blades 39, may be provided with lugs 41 having threaded holes to accommodate the screws 36,

and these lugs are best arranged on the sides of the blades which do not impel the air, in order to avoid obstacles to the flow thereof.

The angles which have been specified above are those found most satisfactory for the particular size of burner illustrated, which burner is shown substantially four-fifths full scale on Fig. 3. These angles may of course vary. It is desirable that the lead angle as determined between points 4| and 42 be as great as possible to provide for increased length of the blade which is desirable for obtaining increased air capacity and pressure. The lead angle is more or less determined by the size of the fan hub; and in larger size burner fans wherein larger hubs are feasible, it may be much greater than that of eighty-six and one-half degrees (86%). The angle, 39a of twenty-two degrees (22) is also variable within reasonable limits for different size burner fans, it being important that such angle be not so great as to permit air slippage but yet large enough to reduce as much as possible the tangential discharge component of the air which results in eddy currents and consequent loss of power.

As previously related, the blade is curved between points 4| and 45, such curvature being preferably no greater than that necessary to produce substantially true streamline flow at the inlet, soas to reduce turbulence. The portions of the blades between points 45 and 44 is made straight to prevent change in direction of the air while flowing between the vanes, to thereby also reduce turbulence.

Air enters the fan from the right, as seen on Figs. 3 and 8, through the central opening of the annular plate 31. The blades 39 increase in width from the hub outwardly to the inner periphery of the annular plate 31, and they decrease, as do the blades 46, in width from there outwardly to the outer periphery of the annular plate 31 which is inclined to'the axis of rototion and has the shape of a truncated cone, as seen on Fig. 8. This presents to the incoming air a dish-like set of blades forming a concave conically shaped air intake within the fan, and

fan'and impel it along their convex sides outwardly at right angles to the direction of entry into the fan. The outer periphery of the annular plate 31, the outer ends of the vanes 39 and 46, and the outer periphery of the plate 35 terminate on the same circular cylindrical surface.

The casing 2| is flared outwardly as at 48 to confine and direct the air thrown outwardly by the fan. There is very little; if any, turbulence (eddy currents) in such air. Its motion is principally toward the left as seen'on Fig. 3, and

fan and in the direction of rotation of the fan, which occurs in centrifugal fans, is substantially decreased. This airis picked up and brought in toward the axis of the device to be discharged forwardly overv the end of the oil feed which outwardly by the fan, I provide annular plates with vanes between them to form air paths leading toward the center. A member 49 forming an extension of the casing and attached to the casing part 48 by screws 490, extends from this trally inwardly. A plate 5| is attached thereto,

as by means of screws 52 accommodated in lugs 53 on the convex sides of the blades. A' central forward extension 54 of the plate 5| directs the air flowing between the stationary vanes forwardly about the oil discharge cup 55 through which the oil is discharged to the left as seen on Fig/3. A nozzle member 56, providing, an air, discharge opening, is attached to the casing plate 49, as by screws 56a, to receive the forwarded air, and interiorly thereof are deflecting vanes 51 shaped an'd arranged to give the air a rotative movement counter to that of the oil. Turbulence and eddy currents have thus been minimized in thevair passing from the place of entrance into the fan up to the place where it is used.

Oil flows through the stationary pipe 29 and through the conventional nozzle 6| at the end thereof.

struction and preferably has an opening 62 at the upper side thereof to discharge the oil in a stream against the interior of the rotating oil discharge cup 55 which is mounted on and attached to the motor shaft, as by screws 55a. Due to its speed of rotation and its conical interior tapering outwardly toward the discharge end, the

of oil which is under at least sufiicient pressure to' make it-flow to the burner at the maximum desired rate. From the fitting 63 the oil flows through a valve 66 which may be of any suitable conventional construction, and then through the pipe 68 into the hollow lug 30 from whence it flows through pipe 29 and out through the nozzle 6!. Y r

Such oil valve is opened and closed by an actuating. stem rotatable throu'gh a range of over one hundred and eighty degrees (180) between the wide open and shut positions. The, actuating stem of the valve which controls the feed of oil to the burner is, in'tum, controlled by'an actuating or, control lever which preferably is limited to a swing of about ninety degrees (90) for convenience of operation, but which is so connected with the valve that such a ninety deof movement. This permits of a short stroke -of the lever adjusted by the operator to set the valve anywhere between the range of wide open to closed, and makes the control of the device more convenient and the device itself more com tity of oil fed to the burner. This nozzle may be of any suitable conof which has a slot II "to accommodate the pin II. This pin is at the end of link 13 plvotally connected at 14 to the crank 15 attached to the sprocket 15. A sprocket chain 11 extends about this sprocket and about a smaller sprocket 18 fixed on the valve control stem 180-, the rotative movement of which opens or shuts the oil valve.

The operating handle 51 rides over parallel guides 19 between which the rod 68 extends, and either one or both of these may be marked to indicate the comparative amount of 011 being fed when the operating handle is in any particularposition. The guides are connected to each other at both ends to limit the movement of the handle 61. The limit of movement may be pre-adjusted, for example by means of an adjustable screw 19a threaded into the connection between the guides I9 atan end thereof, and a lock nut 19b to hold it fast in adjusted position. The end of the movement of the handle 61 may thus be adjusted. The mechanical movement so far described has' the function of making the member -which opens and closes the oil valve rotate through a greater angle than the movement of the operatinghandle,

I provide a connection between the operating handle 61 and a reciprocative air valve shutter plate 58 which controls the flow of air tov the fan 'to that required for any particular quan- This p1ate'58 is mounted directly a't'the fan intake for sliding ,movement toward and away froma baffle plate or valve seat 59 located closely adjacent to the fan intake between the fan and the motor. This baille plate is fastened by means such as screws 59a to the lugs 24, and additional lugs 24a may be provided for a similar purpose. The valve plate 58 is convexly conical or dish-shaped complementary to the fan intake and together with the baffle plate or seat 59 directs all air into the fan intake,,to thereby provide a substantially uniform cone-like flow of air converging into the.

fan inlet well within the fan. Thus atmospheric air can enter the burner through the wide opening 22 to a position closely adjacent the inlet to thefan and be consequently admitted into' lugs 24'to guide the plate in straight axial move- 'ment. The plate is attached to a rod by means of a screw 8| passing through the lug 60. This rod is capable of longitudinalslidlng movement in perforations through the lugs 26 and 21. An ear or lug'84 is fastened to the rod in adjustable position'thereon and is forced to the left as seen on Fig. 3 by means of a compression spring 85. A pin 86 projects from the lug 84 and rides against a cam 81 attached to a cam-carrying plate 88 mounted on the shaft 89 upon which the sprocket I6 is mounted, so that this plate 88 will rotate with this sprocket. Cam 8! has a slot 90 passing through the center thereof so that the shaft 89 may pass therethrough, and is also provided with two additional slots 9| and 92 for permitting screws Ma and 92a to pass therethrough to enter threaded openings in the camcarryingplate 88. The three slots permit of radial and circumferential adjustment-of. the cam to supply more oil, the cam will be rotated so that it will push the pin86 and thereby effect movement of rod 80; the spring 85 always maintaining the pin 86 in contact with the cam, so that when handle 61 is moved to close the oil valve, the shutter '59 will also be moved toward minimum air feed position.

The degree of firing may be controlled merely by movement of the operating handle 61 which as is now apparent controls the rate of flow of oil to-the burner and adjusts the rate of feed of air for the maximum efliciency of the burner at the particular rate of feed of the oil. The cam has a dwell portion 91a in which rotation of the cam does not change the position of the pin 86 nor of the valve plate 58, because at the lower firing the spring 99. In case it is desired to mount the ranges when the burner is operating at substantially or close to minimum capacity it is best to be able to vary the flow of oil without changing the rate of flow of air. I

A set screw 99 fitting in a threaded perforation in the lug 84 may be fixed in adjusted relation to the said lug by a lock nut Hill. The end of this screw abuts against the shaft 89 and thereby holds the lug 94 at not less than 'a predetermined distanceto the right and so prevents the feed-of air being less than a predetermined minimum. This permts of varying the minimum amount of primary air independently of the cam, and insures that when the burner is shut oil! and then subsequently started, there will always be a supply of air immediately available.

I usually attach my burner to a hinge plate 94 which is attached to the furnace wall, and which is shaped to form the outer nozzle 95 between which and the nozzle 59 is an annular path through whichthe secondary air-supply of combustion may flow by natural draft. The burner is attached to the hinge plate by means of the hinge ll'il so that it canbe swung away from the opening or maintained in operative position by the usual-latch 91 maintained in position by burner on a pedestal, a screw threaded opening 93 is provided to receive the pedestal, such opening being plugged when the burner is mounted v on the hinge plate.

Air enters the casing through the opening 22, passes around the motor and thereby cools it, and is then drawn of! to the left as seen in Fig. 3, passing between the lugs 24 and between the valve plate 68- and the baflie plate 59, the

quantity of flow of air being controlled by the position of the valve plate relatively to the baflle plate. The entire volume of air is admitted at the central fan intake without interference, and the fan blades and 49 and the walls 35 and 31 of the fan casing are so arranged that the path of air flow has substantially the same total cross sectional area throughout its flow through-the fan, so that all the forces applied to the 'air will be translated only into velocity with no squeezing or expansion of the air as it progresses through the fan, with the result that turbulence or eddy currents will be avoided. In other wordsgthe total area of inlet 39 is substantially equalto the total discharge area at the periphery of the fan, and each of these total areas is substantially equalto the total area of any intermediate cross section. This is accomplished primarily due to inward taper of the fan from the inlet to the periphery, and by having the air flow through all of the space between the vanes or blades. The cross sectional area of the air path continues to remain unchanged after the air leaves the fan. The discharge of air from the fan is uniform all around the periphery of the fan, which results in a constantly even flow, the direction of which is changed on passing from the casing part 49 to the part 49, where the cross sectional area of the air path is' substantially the same as that in the fan. The cross sec-- tional area of the air path remains substantially unchanged until the air has entered the nozzle or air discharge opening 58 which is close to the locus of use of the blast of air. With this in view, the casing part 49 is bent forwardly as it approaches the center so that the spaces between the blades 5!! become deeper as they become narrower toward the center, thus-maintaining constant the cross sectional area of the air path. Not only is the path of the air through the fan maintained constant in cross sectional area, but it remains the same almost up to the point of exit of the air from the nozzle, and in fact throughout my burner it is preferably substantially unvarying in cross section except where variation is necessary as at the air control valve. The air control valve is directly at the intake'of air into the fan, which, as previously related, is important because it allows the air to enter the fan under atmospheric conditions. The path of the air is the least tortuous .possible, and there isno throttling of the air before it reaches the fan.

Turbulence and eddy currents in the forwarded air are thus not only minimized after the air enters the fan, but also' from the place of entrance into the burner at the opening 22 almost of. turbulence, is minimized in my device. With the fan blades having the spiral like shape including the curved portion at the intako and the straight portion from there out to the periphery, the air is thrownout from the fan in a direction having more of a radial component and less of a tangential component than if the blades were merely straight. This also tends'to minimize the amount of turbulenceor eddy currents since by this arrangement there is less change of direction of the air than formerly. I

Straight radial blades in the fan eject the air therefrom with a greater tangential component, thus causing more of a. change in direction and greater turbulence. The curved part of the blades increases the blade length, as does the obliqueness of the straight part. Increased'blade length and lack of slippage both contribute to.

increased velocity of the airs The gate type of valve for controlling the rate of flow of air oflers a restriction in the path thereof, whereas the reciprocating type permits of an uninterrupted now of air converging toward the fan intake.

'My'burner may thus be controlled very simply.

' easily, quickly and effectively by a simple move-' ment of a single control lev'en, In addition to 15 this the burner operates very efllciently at all settings of the control lever because the supply of air is the optimum for that rate of flow of liquid fuel to which the burner may be adjusted by moving the operating handle 61. The oil follows the simplest path through the device and is prepared for burning only as it approaches the outlet. The air likewise follows the simplest path through the burner and the rate of flow thereof is controlled immediately at the entrance into the fan.

The structure of my device reduces the size of the burner per unit of output. and also reduces the power required to operate it per unit 'of output.

Various details have been referred to for the purpose of describing but not limiting the inand a valve plate within said casing having with i reference to said intake a convex shape complementing that of said intake so as to flt substantially within said intake in the closed position thereof and mounted for reciprocating movement axially of said fan at said baille and and intake.

2. A blower comprising a casing, a fan within said casing provided with vanes and an intake within and centrally thereof, said vanes forming an air path of substantially uniform cross section to avoid constriction of the-air in its flow therethrough, a bailie mounted within said casing all around said intake, said intake being con;

' cavely dish-shaped, and a valve plate within said casing having with reference to said intake 9.

- convex shape complementing that of said intake so as to fit substantially within said intake in the closed position thereof and mounted for reciprocating movement axially of .said fan at said baille and intake to provide and control an unthrottled hollow cone-like path for the air into 'said intake shaped substantially like said intake.

3. A blower comprising a casing, a fan rotatable therein including spaced apart plate members having vanes positioned therebetween and having a concave shaped inlet within and about the axis of rotation thereof ,the' parts of the fan including the vanes being so arranged as to provide substantially the same cross sectional area for the passage of air from adjacent the inlet to the discharge of the fan, the casing being provided with an opening for. ingress of air to the fan, and

. means for controlling the flow of air including a adjacent one end thereof and with a chamber,

means'segregating said chamber into a fan comipartment and another compartment communicating with said air discharge opening, a rotatair in its passage, therethrough comprising spaced apart plate membersand spaced apart impeller blades positioned between said plate members, the plate members, converging toward each other in a direction toward the periphery thereof, one of said plate members having a-centrally disposed aperture for inlet of air and' said blades being constructed adjacent said'aperture to provide an inwardly dish-shaped 'air inlet about'and within the axis of rotation of the fan, all of the space between said impeller blades providing passages for flow of air therethrough, the cross sectionalv area of said passages being substantially uniform throughout, said casing being open adjacent said air inlet to provide for unthrottled ingress of air, and means for controlling the flow of air including a valve plate within said casin having with reference to said inwardly dishshaped inlet a convex shape complementing that of said inlet so as to fit substantially in said inlet in the closed position thereof'and mounted for reciprocative movement axially of" said fan at said inlet to provide and'control an unthrottled hollow cone-like path for the air into-said inlet shaped substantially like said inlet.

5. A rotatable fan blower construction for an oil burner of ,the rotary oil-discharge cup type comprising a casing having an air discharge opening, a, hub rotatable about the axis of said air discharge opening, spaced apart plate members secured to said hub, one of said plate mem- 5 able fan in saidfan compartment constructed to preclude substantialsqueezing or expansion of bers having an air inlet opening centrally there- I of about said axis, spaced apart impeller blades between said plate members, said impeller blades having straight portions lying between said opening and the periphery of said plate members and extending outwardly in a direction obliquely backwardly with respect to the direction of rotation of said fan, at least some ofsaid impeller blades also having portions which are spiral-like and extend-inwardly from said opening toward the center of rotation in a curve and meeting. said hub at positions spaced forwardly in the direction of rotation from the points where radial lines from the outer ends of said blades meet said hub, the straight portions of said blades decreasing and the spiral-like portions of said blades increasing in width away from the center of ro- .tation. Y

6. A'blower construction for an oil burner of having with reference to said intake a convex shape complementing that of said intake so as to flt substantially within said intake in the closed position thereof, said casing having an air inlet between said ends and adjacent said fan intake to cause air to pass through said casing and to enter said fan under substantially atmospheric conditions. a

' .7. A blower construction foran oil burner of the rotary oil-discharge cup type comprising a casing having an air discharge opening adjacent one end thereof, a motor adjacent the opposite end of said casing and enclosed thereby, a rotary fan driven by said motor to rotate about the axis'of said discharge opening and having a concavely dished air intake about, the axis of rotation of and within said fan and connecting with the interior of said casing, a reciprocative shutter valve within said casing at said intake and having with reference to said intake 'a convex shapecomplementing that of said'intake so as to fit substantially within said intake in the closedposition thereof, and an annular baiiie within said casing between said valve and said fan to control the flow of air into said intake, said casing having an air inlet between said ends and adjacent said fan intake to cause air to pass through said casing and to enter said fan un'der. substantially atmospheric conditions.

'8. A blower construction comprising a substantially tubular-like casing which is imperiorate at one end and has an air. discharge opening at the other end, a-moto'r positioned within said casing between said ends and having a shaft rotatable about the axis of said discharge opening, a rotatable fan positioned between said motor and said discharge opening and drivable by said shaft about the axis of said discharge open- 8,. and fan having a centrally-disposed con: cavely dished air intake, and a valve plate within said casing adjacent said intake having with reference to said intake a convex shape complementing that of said intake so as to fit substantially within said intake in the closed position thereof and mounted for reciprocative movement along said axis in directions toward and away-from said intake to provide and control a substantially unthrottled hollow cone-like path for the flow of air into said intake shaped substantially like said intake, a peripheral portion of said casing located between said ends being provided with an air inlet adjacent said valve plate to provide a substantially unthrottled path for the flow of alr'i'rom the casing inlet to the fan intake, whereby emciency'is enhanced.

9. A blower'construction comprising a substantially tubular-like casing which is imperforate at one end and has an air discharge opening at the other end, a. motor positioned within said casing between said ends'and having a. shaft rotatable about the axis of said discharge opening, s. rotatable fan positioned between said motor and said discharge opening and drivable by said shaft about the axis of said discharge opening, said fan beingprovided with vanes forming 'an air path of substantially uniform cross section to avoid constriction or expansion of the air in its flow therethrough and having a centrally disposed concavely dished air intake, a valve plate withinsaid casing adjacent said intakehaving with reference to said intake a convex'shape complementing that oi said intake so as to ilt substantially in said intake in the closed position thereof and mounted for reciprocative movement along said axisin directions toward and away from said intake to provide and control a substantially unthrottled hollow cone-like path for the how of air into said intakeshaped substantially like said intake, a peripheral portion of said casing located between said ends being provided with an air inlet adjacent'said valveplate to provide a substantially unthrottled path for the flow of air through said fan from'said casing inlet to said fan intake, whereby the path for the ilo'w chair from said casing inlet to and through said fan is substantially unthrottled and emciency enhanced.

l0.-A blower construction comprising a substantially tubular-like casing which is imperforate at one end'and has an air discharge opening at the other end, a motor positioned within said casing between said ends and having a shaft rotatable about the axis of said discharge opening, a rotatable fan positioned between said motor and said discharge opening and drivable by said shaft about the axis of said discharge'op'ening, said fan being provided with vanes forming an air path of substantially uniform cross section to avoid constriction or expansion of the air in its flow therethrough and having a centrally disposed concavely dished air intake, a valve plate within said casing adjacent said intake having with reference to said intake a convex shape complementing that of said intake so as to fit substantially in said intake in the closed position thereof and mounted for reciprocative movement along said axis in directions toward and away from said intake to'provide and control a substantially unthrottled hollow cone-like path for the flow of air into said intake shaped substantially like said intake, a peripheral portion of said stantially tubular-like casing extending along an axis and which is imperforate atone end and has an air discharge opening-about said axis at the opposite end, said casing being provided with an enlarged chamber between said ends extending transversely across said axis, means segregating said chamber-into a fan compartment positioned to communicate with the portion of said casing adjacent said imperforate end and into another compartment communicating with said air discharge opening, a motor within said casing between said imperforate end thereof and said fan compartment and'having a shaft extending along androtatable about said axis, a fan in said fan compartment mounted on said shaft for rotation about said axis and having a centrally disposed air intake about said axis, and a valve plate within said casing between said motor and said fan mounted for reciprocative movement along said axis in directions toward and away from said intake to control the flow of air into said intake.

the periphery of said casing between said fan compartment and said imperi'orate end having an air inlet'opening adjacent said valve plate.

12. A blower construction comprising a substantially tubular-like casing extending along an axis and which is lmperforate at one end and has an air discharge opening about said axis at the opposite end, said casing being provided with an enlarged chamber between said ends extending transversely across said axis, means segregating said chamber into a fan compartment positioned to communicate with theportion of said casing adjacent said imperforate end and into another compartment communicatingwith said air discharge opening, a motor within said casing between said imperi'orate end thereof and said fan compartment and having a shaft extending along and rotatable about said axis, a fan in said I fan compartment mounted-on said shaft for rotation about said axis and having a centrally dis- 7.

posed air intake about said axis, said intake being dished concavely from a face of said fan at a locus spaced from said axis to a locus adjacent said axisbetween the faces of said fan to form said intake well within the fan, and a valve plate within said casing between said motor and said fan mounted for reciprocative movement along said axis in directions toward and away from said a provide a substantially hollow cone-like path for theflow of air into said intake shaped substantially like said intake, the periphery of said casing between said fan compartment and said imperforate end having an air inlet opening adjacent said valve plate 13. A blower construction comprising a subso stantially tubular-like casing extending along an opposite end; said casing being provided with an "to communicate with the portion of said casin adjacent said imperforate end'and into another axis and which is imperforate at one end and has an air discharge opening about said axis at the 'enlarged'chamber between said ends extending transversely across said axis,'means segregating said chamber into a fan compartment positioned tween said imperforate end thereof and said fan compartment and having a shaft extending along and rotatable about said axis, a fan in said fan compartment mounted on said shaft for rotation about said axis'constructed to preclude substan- A tial squeezing or expansion of air in its passage therethrough comprising spaced apart plate members converging toward each other toward the periphery thereof and spaced apart impeller blades positioned between said plate members,

impeller blades being of decreasing width from adjacent the edge of said aperture to a locus adjacent said axis to form in cooperation with said aperture a concavely dished air intake within the fan, and a valve plate within said casing between said motor and said fan mounted forreciprocative movement along said axis in directions to,- ward and away from said intake, said' valve plate having with reference to said intake a convex shape complementing that of said intake so as to fit substantially within said intake in the closed position thereof and provide a substantially hollow cone-like path for theflow of air into said intake shaped substantially like said intake, the periphery .of said casing between-said fan compartment and said imperforate endhav ing an air inlet opening adjacent said valve plate.

HARVEYE,m 'lzcoc so '10 one-of said plate members having a central apertrue about said axis for inlet of air and said Patent Ho. 2,218,6 5

CERTIFICATE OF qpnmagnoy. v

October 22, 1914.9, HARVEY E. HENRIKSEN.

Itis hereby certified, 't'hat error appear s in the printed. afieoi f ication 01 the above numbered patent requiring coi'rection'as follows: Page 2, first column; line 51-52, for. "variour" read "variouspage 5, second column,

lines l1 and 1-2, :foz the fiords "and within the axiaof rotation of" read .--th eaxis of rotatloz; of and'w1th1n-; page 6, se.c ond.co lmnn,'] .ine 2, claim 9, before "enhanced" inaeivt is--; and that'the said Letters Patent should be read with thifs correction therein that the same may conform to the rec- 0rd or thehca se 1n the Patent orficq Signed and sealed this 5rd. day of December, A. D. 1914.0.

v Henry- Van Arsdale,

(Seal) Acting Commissioner of Patents. 

